1. Field of the Invention
This invention relates to a process for fabricating a color filter.
2. Description of the Prior Art
A color filter is widely used as a color plate for limiting oblique luminous flux, a color face plate for Braun tube display, a plate for photoelectric transducer for copying, a filter for color television camera of a single tube type and the like.
In particular, as a technique for producing semiconductors has recently developed, a solid pickup element has been used as an element for converting two dimensional images to electric signals in place of conventional pickup tube. For example, a solid pickup element called "CD" (charge coupled device) or "BBD" (bucket brigade device) contains a great number of finely divided light receiving portion and a driving circuit for taking out information from the light receiving portion in one chip, and for picking up color images, a color filter corresponding to the surface of the finely divided light receiving portion should be provided.
A color filter used for a solid pickup element and in the other field has been recently demanded which is elaborate and of high resolution and good durability since high resolution of color image and smaller size of a color image converting apparatus are desired.
A color filter is usually a filter where color elements are arranged in a form of mosaic or stripe. As color elements, blue (B), red (R) and green (G) are most often used.
A representative process for fabricating a color filter comprises forming a color element receiving layer by coating a resin such as polyvinyl alcohol, gelatine and the like on a support and applying a coloring matter to the color element receiving layer. For producing each of red, green and blue color elements, a mask is formed on a color element receiving layer usually by using a photoresist and a coloring matter is applied to predetermined portions and then the mask is removed by etching. This procedure should be repeated three times and therefore, the fabricating process is very complicated. In addition, pinholes and defects are liable be formed during the fabrication and it has been desired to produce a color filter free from such drawbacks in good yield.
When a color filter is formed directly on a light receiving element such as a solid pickup element, the formation and removal of the photoresist mask are conducted by a wet treatment and therefore, the light receiving element is liable to be adversely affected by the etching solution.